Transit concrete mixer



June 20, 1967 J. s. WALLACE TRANSIT CONCRETE MIXER 2 Sheets-Sheet 1Filed Nov; 26, 1965 1N VENQTOR. JAMES 5. WALL/ME June 20, 1967 J. 5.WALLACE 3,326,537

TRANS IT CON CRETE MIXER Filed Nov. 26, 1965 2 Sheets-Sheet 53 INVENTOR.JAMES .5. 14/444,405

Patented June 20, 1967 3,326,537 TRANSIT CONCRETE MIXER James S.Wailace, 1732 Alki Ave. SW., Seattle, Wash. 98116 Filed Nov. 26, 1965,Ser. No. 509,726 Claims. (Cl. 259-177) The present invention concerns atransit concrete mixer of a special type, not ordinarily one of a sizefor regular commercial use, with a capacity of several cubic yards ofconcrete, nor yet one that is intended to be filled with concretealready mixed at a ready-mix plant (which plants are usually distantfrom residential neighborhoods where the user would wish to pour it),but rather one that is intended for rental to a householder who wishesto pour a cubic yard or so at a time, and who can obtain measuredquantities of sand, gravel, and cement at a neighborhood source ofsupply of the separate ingredients, and who after adding water transportthe whole to his site, mixing en route, and using his automobile to haula trailer whereon the mixer is mounted. The aggregates and cement andwater would be within a drum mounted rotatably upon the trailer chassis,and their proportions could be closely controlled. Upon arrival at thesite the cement would be ready to pour, having been mixed en route, andcan be delivered into forms directly, or into a wheelbarrow, at whateverrate is convenient or necessary.

It has been noted that ready-mix concrete plants are usually locateddistantly from residential neighborhoods, where such a user might wishto place the concrete. There usually are, however, sources of supply inor near such neighborhoods where bags or other measured quantities ofaggregates and cement can be obtained, and the mixer of this inventionenables the user to obtain the same readily, and near by, and to mix thewhole in the desired proportions, hence he avoids on the one hand, thenecessity of ordering and disposing of a minimum load of several yardsof concrete when he can only use a part thereof, and on the other hand,of a long haul from a distant ready-mix plant with the small quantitythat he needs, perhaps not quite of the correct proportions, and thepossibility of setting of the concrete within the drum while en route tohis site.

More particularly, aside from the convenience alforded by such a mixer,the drum would be so mounted and driven, upon the trailer, as to renderthe trailer unit extremely simple and free of the likelihood ofcomplications, particularly in its drive and in its mechanism.

For instance, it is not feasible to rotate the drum from the engine ofthe tractor automobile, as a commercial transit concrete mixer is drivenby the power take-off of the engine that drives the truck whereon it ismounted, nor is it feasible to mount upon the trailer chassis an engineintended solely to rotate the drum. This would add the weight of theengine, its fuel tank, and cooling system to the trailer, would addexpense to the renting agent that the renter would have to pay, andwould increase the possibility of a stoppage or breakdown en route,unknown to the automobile driver, or which he would be unable to remedypromptly, with consequent danger of setting of the concrete within thedrum. Furthermore, such a drive system for the drum would involveexpense and down-time while the system was being serviced or repaired.

According to the present invention the drum is mounted upon the trailerchassis in such manner that, during transportation, it is rotated bymeans of a drive connected to a road wheel or wheels of the trailer.Such a driver, however, must be of a special nature; in particular, itmust not be directly and rigidly connected to such driving wheels, butit must be indirect to the extent that it becomes elfective only duringforward motion of the trailer, and also at road speeds above apredetermined minimum. A torque converter drive will satisfy therequirements. Thereby the drum will not begin to rotate until thetrailer has acquired a predetermined road speed of, say, fifteen milesan hour, and the tractor automobile will not be burdened with the addedtask of rotating the drum at the time it must start the entire loadmoving forwardly, not until that starting burden has slackened, and thecar and trailer have gained momentum. Thereafter the drive to therotating drum gradually becomes more positive as the forward speedincreases or maintains its rate.

Moreover, with the torque-converter interposed between the drivingwheels of the trailer and the drum, an abrupt stop of the tractorautomobile and the trailer can have no adverse effect, for rotation ofthe drum under its acquired momentum can continue in such event, butwill not drive forwardly the trailer or the automobile, whereas if thedrive were direct and rigid the rotational momentum of the drum and itscontents would tend to continue rotation of the driving wheels, and thedriver of the tractor car would lose control of the vehicles. Anaccidental collision, or jack-knifing of the trailer, could easilyresult in such a case.

It is also an object of the invention so to mount the drum that it istiltable readily and with little effort, preferably manually, from itstransporting position to its dumping position, and back again, by reasonof the nature of the mechanism and the location of the center of gravityof the drum and its load of concrete, yet it is securely held in itstransporting position, wherein its weight assists in assuring properrotation of the drum, and in maintaining the drum against dumping.

Also, in connection with the mounting of the drum for driving, it is anobject to alford a certain minimum yieldability to the weight of thedrum, yet without impairing the positioning or driving of the drum.

Also, it is an object to design such a transit concrete mixer that theload will be properly distributed between its two axles and theirsprings, regardless of the attitude of the drum.

In particular it is an object to provide such a transit concrete mixerthat is of simple design, that has a minimum of complications in itsdrive and its dumping, that can dump concrete in small increments ifrequired, and that is well suited for use by users who may have onlyminimal knowledge of mechanisms or of engines, yet can be kept c ean andcan be used repeatedly in such service.

With these and other objects in mind, as will appear more fully as thisspecification progresses, the invention comprises the novel transitconcrete mixer shown in an illustrative form in the accompanyingdrawings, and as will be described in detail hereinafter, and defined inthe claims.

FIGURE 1 is a side elevational view, broken away in part, showing themixer in its traveling and mixing disposition, and FIGURE 2 is a likeView, in the dumping position.

FIGURE 3 is a plan view of the mixer, illustrating primarily its drivingand dumping mechanism, with the drum shown largely in phantom, in itstraveling disposition.

FIGURE 4 is a rear elevational view of the mixer, with the drum in itstraveling disposition.

Mixing of the concrete occurs within a drum 1, open at its rear end forloading and dumping. This drum is mounted for rotation about itslongitudinal axis by means of guide rollers 10 (FIGURE 1) mountedexteriorly of the drum about a circle in the vicinity of its loadedcenter of gravity CG, and rolling within a circular track 11. Thisparticular mechanism might be otherwise designed, however. The track 11is tiltable about a diamthrough chains etral tilting axis 12 carried atthe apices of opposite longitudinally directed triangular or A-frames 21rising from the trailers chassis 2, and a forward yoke 16 ported by roadwheels 20, 22, preferably four in number,

carried by the respective forward'and rearwad axles 23, 24. One axlecould serve, 'but for even support of the load without bearing downheavily upon the tractor car, and for avoidance of exceeding axle-loadrestrictions, two axles are preferred. Each axle may support the chassisthrough springs 25, 26. The trailer is drawn by a tractor car to whichit is connected by any suitable or conventional trailer hitch 27.

As the trailer is being pulled forwardly, its road wheels 20, 22 rotateby reason of their contact with the roadway. One pair of wheels, forinstance the forward wheels 20, may be each independently journaled uponthe. ends of their axle 23. The other pair, in this instance the rearwheels 22, are fixed upon the ends of separate half-axles 24, which arejoined through the differential 28, to rotate a forwardly directed drivemechanism that includes a drive shaft 30 and a torque converter 3. Thedrive shaft is connected between the differential 28 and the primaryrotor of the torque converter by means of universal joints 31. Thedetails of the torque converter are not shown, since such mechanism iswell known, and any suitable unidirectionally driving converter can beemployed.

The torque converter 3, when turning at a speed such as to effectpositive drive of the load (which consists primarily of the rotatingloaded drum), rotates a longitudinal shaft 40 journaled beneath thechassis 2, and 41, 42 it drives opposite jack shafts 43, 44, alsojournaled beneath the chassis. Fast upon the jack shafts are therespective driving wheels 4 and 4a, and 4' and 4a rotative about axesgenerally paralleling the drums rotative axis. These wheels contact androtate the drum 1 when the latter is fully in its transporting position(FIGURES 1, 3, and 4).

It will be noted that the forward end of the drum is of frusto-coni-calshape, sloping forwardly towards its axis from a largest circumference,and its rear end also slopes more gently from that largest circumferencetowards its open rearward end, although a more steeply sloped terminalflange 13 may be used there, to insure retention of the load until it isready to be dumped. In the transporting position of the drum its forwardfrusto-conical end rest upon the wheels 4, 4', 4a, and 4a. To minimizeshocks upon the chassis and the driving mechanism, it is preferred thatthese driving wheels have pneumatic tires. It will be noted that in thetransporting position of the drum the CG of the loaded drum is forwardsomewhat of the transverse tilting axis at 12, and tends to maintain:contact of the drum with the driving wheels.

In order to avoid mechanical complications, and to afford close control,dumping of the load is preferably effected manually. A stem 14 isintegral with the drum, and projects forwardly through the yoke 16 andalong the drnms axis. A collar Si) is slidable lengthwise of stem 14,and is connected flexibly to two links 51 that at their outer ends areflexibly connected to nuts that are threaded on oppositely threaded endsof a transverse right-and-left screw journaled upon the chassis 2. Thescrew 5 is rotatable by hand-for example by a hand crank 53 connected tothe screw 5 by suitable mechanism Other specific means can be used toshift the collar 50 for tilting the drum.

The drum is tilted from its transporting position by turning the handcrank 53. The nuts 52 approach, from the outspread position of FIGURE 3;the collar 5 urges the stem 14 upwardly, tilting the drum, andeventually the collar 5 moves towards the drum, along the stem 14. Thefinal dumping position is at FIGURE 2. The tilting of the drum andconsequent rearward displacement of its 4 load of concrete shifts the CGof the whole re-arwardly, to some such position :as is shown in FIGURE2. Concrete spills from the open rear end of the drum into a form, or awheelbarrow, and by means of the manual control of dumping the amountspilled is controllable quite closely.

When a householder has a small concrete job to accomplish, such aslaying a walk-way, he rents the trailer and a trailer hitch forapplication to his car, and buys correctly measured quantities of sand,gravel, and cement, which goes into the drum. The correct amount ofwater is added, and he begins to drive away. At first starting up, hiscars motor is burdened with the added load of the trailer and itscharge, so he starts slowly. The start is so slow that the torqueconverter 3 is ineffective to drive, and merely idles. As his speed andmomentum increase, say to fifteen miles per hour, the torque converterwill begin to drive the wheels 4, 4', 4a, and 4a, and the drum 1, and atnormal road speeds the drum will continue to rotate, mixing its charge.Should it be necessary to brake the car suddenly, the torque convertercan over run its drive shaft 30, and the forward momentum of the trailerand its load will have a negligible effect upon the car, nor will therebe an appreciable tendency to jack-knife the trailer and the car.Arrived at his destination, the load of concrete is dumped by use of thehand crank 53, and as much or as little as is desired can be thusdumped. Finally, all concrete having been dumped, the interior of thedrum receives water, and this washes out the drum during the returntrip.

The A-frames 21, from which the load is supported, distribute the loadquite equally between the forward and rearward axles 23, 24. The forwardleg of frame 21 is approximately centered midway of the length offorward spring 25, and the rearward leg of the frame is approximatelycentered midway of the length of rearward spring 26. The tilting axis 12at the apices is generally midway between the two points where the legsjoin the chassis 2. The circumferential track 11 is so located and thedrum is so shaped that the loaded CG of the drum is a little forward ofthe tilting axis at 12, when the whole is in the transporting position,wherefore the load bears upon its driving wheels, yet in the act ofdumping the CG moves to the rear of the tilting axis at 12, andsubstantially the entire load can be dumped, in controlled quantities,with no great effort. No power source is required,

other than the road wheels, either for mixing or for dumping. The userneed have no experience with mechanisms, and only needs to be sure todump the load before it sets within the drum, and to place washingwaterwithin the drum after the load has been emptied.

The invention has been described as mounted upon a trailer chassis, andno doubt will be so mounted in most cases. However, the drum could bemounted upon the chassis of a truckfor instance, a truck having no powertake-off, and smaller than the usual transit concrete truck. The roadwheels can still be so connected as to drive the drum. When a chassis isreferred to in the claims, this may be taken as the chassis of a traileror the chassis of a truck, and in either case the drum is rotated fromthe road wheels, rather than from a power take-off.

What is claimed is:

1. A transit concrete mixer comprising a vehicle chassis mounted uponroad wheels, a drum, means to support said drum from the chassis forrotation about the drums axis and for tilting movement about atransverse axis, means for thus tilting the drum between a transportingposition and a dumping'position, an impositive drive means mounted uponthe chassis in position to engage the drum externally, and constitutingthe sole means to rotate the same, when the drum is fully in itstransporting position, said drive means being operatively connected tothe road wheels, to be driven by the latter.

2. A transit concrete mixer comprising a vehicle chassis mounted uponroad wheels,'a drum, means to support said drum from the chassis forrotation about the drums axis and for tilting movement about asubstantially horizontal axis transverse to the drums rotational axis,means for thus tilting the drum between a transporting position and adumping position, frictional means engaging the drum externally, whenthe drum is in its transporting position, for rotating the drum, anddrive means interposed between said drum-rotating means and said roadwheels, for effecting rotation of the drum while the vehicle istraveling along a roadway.

3. A transit concrete mixer as in claim 1, wherein the drive meansincludes means arranged to effect rotation of the drum only afterattainment of a predetermined road speed by the vehicle.

4. A transit concrete mixer as in claim 3, wherein the drive means is atorque converter which becomes effective only upon attaining thepredetermined road speed.

5. A transit concrete mixer as in claim 1, wherein the drive meansinclude Wheels mounted upon the chassis in position to engage the drumexternally, and each rotative about an axis generally paralleling thedrums axis, the drum being mounted to locate its loaded center ofgravity, when in its transporting position, somewhat to the same side ofits tilting axis as said drum-engaging wheels.

6. A transit concrete mixer as in claim 5, wherein the driving wheelsinclude pneumatically yieldable tires.

7. A transit concrete mixer as in claim 5, wherein the drum-supportingmeans has its tilting axis disposed adjacent the loaded center ofgravity of the drum, and the drum is of such shape as to dispose thatcenter of gravity to that side of the tilting axis such as will causethe drum to bear upon the driving wheels when it is in its transportingposition, but will cause that center of gravity to shift towards theopposite side of the tilting axis as the drum approaches its dumpingposition.

8. A transit concrete mixer as in claim 1, wherein the tilting meanscomprise a stem directed coaxially of and external to the drum, a collarslidable along said stem,

and means on the chassis engaged with said collar and shiftable toeifect elevation and lowering of the stem as the drum is shifted therebybetween dumping and transporting positions.

9. A transit concrete mixer as in claim 1, wherein the tilting meanscomprise a stem extending coaxially of the drum, a collar slida-blealong said stem, a pair of nuts, one at each side of the chassis andguided for movement transversely of the chassis, each nut "beingoperatively connected to said collar to shift the latter along thestern, away from and towards the drum, and a right-and-left threadedscrew disposed transversely of the chassis and threaded within therespective nuts, to eifect their separation and consequent movement ofthe drum towards its transporting position, or to effect their approachand consequent movement of the drum towards its dumping position. v

10. A transit concrete mixer as in claim 1, wherein the chassis issupported by road wheels upon a forward and upon a rearward axle, andwherein the drum supporting means includes upright triangular frames atthe opposite sides of the chassis, with the tilting axis at the upperapex thereof, the triangular frames Ibeing located to distribute theload substantially equally between the two axles.

References Cited UNITED STATES PATENTS 1,103,534 7/1914 Nye 259-1,332,880 3/1920 Bloom 259171 1,453,634 5/1923 Martin et al 259-1772,176,874 10/1939 John 259-177 2,540,317 2/1951 Baggott 259-1752,680,377 6/1954 Gerst 259177 3,215,411 11/1965 Pitts 259177 WALTER A.SCHEEL, Primary Examiner. ROBERT W. JENKINS, Examiner.

1. A TRANSIT CONCRETE MIXER COMPRISING A VEHICLE CHASSIS MOUNTED UPONROAD WHEELS, A DRUM, MEANS TO SUPPORT SAID DRUM FROM THE CHASSIS FORROTATION ABOUT THE DRUM''S AXIS AND FOR TILTING MOVEMENT ABOUT ATRANSVERSE AXIS, MEANS FOR THUS TILTING THE DRUM BETWEEN A TRANSPORTINGPOSITION AND A DUMPING POSITION, AN IMPOSITIVE DRIVE MEANS MOUNTED UPONTHE CHASSIS IN PORTION TO ENGAGE THE DRUM EXTERNALLY, AND CONSTITUTINGTHE SOLE MEANS TO ROTATE THE SAME, WHEN THE DRUM IS FULLY IN ITSTRANSPORTING POSITION, SAID DRIVE MEANS BEING OPERATIVELY CONNECTED TOTHE ROAD WHEELS, TO BE DRIVEN BY THE LATTER.